[Towertalk] 100M-long boom Yagi for 20M

Hi Yuri,
Using the same software that W6TSW used, YO, one can easily scale any Yagi
from band to band (frequency to frequency) with ease. I have found
excellent correlation. I have scaled numerous VHF Yagis to HF without
problems. Obviously the elements have greater diameters and are much
longer! The present day YO software does an excellent job at frequency
scaling and is especially powerful when using tapered elements.
I have numerous choices of hundreds of designs that I have already built,
tested and shipped to customers over the years. Just for a quick check, I
looked at the design of my 17B2 (17 elements on 144 MHz on a 4.5 wavelength
boom) that Cushcraft sells. It scales to the exact same boom length of the
W6TSW antenna. It does have a few more elements but has about 1.0 dB more
gain, an incredibly clean pattern with high F/B ratio....and over the
entire 20 meter band, not just at 14.150 MHz.
Another example is a 14 element 4.5 wavelength design that I have built on
2-meters that has the almost the same gain (15.53 versus 15.89), a very
clean wide bandwidth BUT a boom length of only 250 feet....70 feet shorter.
For 0.36 dB less gain (I'll challenge you top measure that!), you use two
less towers, quite a savings!
With all due respect to the W6TSW design, we must remember that this is the
year 2003, not 1986, so we must give credit where credit is due. However,
if this gain is to be done on 20 meters again with a Yagi antenna, it would
be foolish to duplicate the same design.
73,
Joe, W1JR
At 09:18 PM 1/13/2003 -0500, K3BU@aol.com wrote:
>In a message dated 1/13/03 8:57:22 PM Eastern Standard Time, W1JR@arrl.net
>writes:
>
> >
> > I have built some VHF designs that can be scaled to 20 meters that will
> > match the beamwidth and meet or exceed that gain on a shorter boom with a
> > much cleaner, broadband pattern and match directly to 50 Ohms!
> >
> > That being said, it sure was a novel idea and a way to configure a
> long HF
> > Yagi.
> >
>
>Hi Joe,
>can you elaborate on agreement between software designs and actual antennas?
>
>VHF antennas allow close verification and measurements.
>
>Yuri, K3BU
>_______________________________________________
>AN Wireless Self Supporting Towers at discounted prices,
>See http://www.mscomputer.com
>
>Wireless Weather Stations now $349.95. Call Toll Free,
>888-333-9041 for additional information.
>_______________________________________________
>Towertalk mailing list
>Towertalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk